With 97.8 percent of the ballots counted from Sunday`s vote, center-left candidate Scioli had 38.4 percent, conservative business favorite Mauricio Macri had 30.1 percent and Congressman Sergio Massa, a dissident from Kirchner`s political movement 20.6.

Argentina`s peculiar primaries, in which voters can pick any candidate regardless of party affiliation, are widely seen as a dry run for the October 25 general elections.

Scioli`s performance will consolidate his position as the front-runner to succeed Kirchner, under whose husband he served as vice president.

But it was not resounding enough to silence the specter of a tough run-off on November 22.

The October election will go to a second round if no candidate wins more than 45 percent of the vote or 40 percent with a margin of victory of at least 10 percent.

With the business community largely hostile to Kirchner`s heavy-handed economic policy, Macri could rally the pro-change vote to defeat Scioli in a run-off.

Seeking to bolster his image as more moderate than Kirchner, Scioli, 58, said he would not be bound by ideology if elected.

"If there`s one thing that characterizes our political sphere, it`s diversity, the way we complement each other while agreeing on the basic issues," he told a press conference.

"What center, what right? I`m going to do what`s right," he responded with pique when asked about his political orientation.Analysts said the result clearly amounted to poll position for Scioli, an offshore power-boating fanatic who lost his right arm in a 1989 racing accident.

"Experience shows the first-place candidate (in the primaries) tends to rise rather than fall," said political scientist Rosendo Fraga of consultancy New Majority.

But Massa could play the spoiler, he added.

"He`s a third force. Where his votes end up will be the key to the final election result. Scioli or Macri, the winner will be the one who best manages to capture Massa`s 20 percent," he said.

All 32 million eligible voters were required to cast ballots in the primaries.

The peculiarly Argentine process is less about parties picking candidates than showing which contender can garner enough votes to become Argentina`s next leader.

Scioli was the only presidential candidate for Kirchner`s Front for Victory (FPV).

Macri, the 56-year-old mayor of Buenos Aires, comfortably won the most votes of the three candidates for the Let`s Change coalition. Massa likewise won easily for his coalition, United for a New Alternative (UNA).The primaries mark the beginning of the end of the Kirchner era for Argentina -- eight years under Cristina and four under Nestor.

Kirchner is entering the final stretch of her presidency with more than 50 percent support, despite a laundry list of woes in Latin America`s third-largest economy that includes a sliding currency and a messy legal battle over defaulted debt from the country`s 2001 economic crisis.

The economy has been alternating between stagnation and weak growth. Unemployment is a manageable 7.1 percent, but inflation is running at 20 percent.

Barred from running again by term limits, Kirchner, 62, is not standing for any post.

Keeping the political dynasty alive, however, the couple`s son Maximo, 38, won his primary to stand as a congressional candidate for Santa Cruz province.

And the adviser seen as Kirchner`s right-hand man, Carlos Zannini, is Scioli`s running mate.

Argentina introduced primaries in 2009 in a bid to make candidate selection more democratic and revitalize a party system gutted by the fallout of the economic crisis, when the country churned through five presidents in two weeks.

But despite the new system, parties have largely continued to pick their candidates through opaque internal processes ahead of the vote.